Washington state attorneys insist that 5-Hour Energy wouldn’t work if it wasn’t for its caffeine content in a fierce attack on the credibility of America’s top-selling shot.

Washington’s lawsuit follows a multi-state investigation where AGs looked at 5-Hour’s marketing, promotion and sales. Led by attorney general Robert Ferguson, it argues the brand has no “competent and reliable” scientific evidence to back-up product claims.

5-Hour Energy sells around 9m 1.93oz bottles per week in the US at around $2.99, which nets approximate $1bn in national sales. But last Thursday Washington, Oregon and Vermont all sued the shot’s maker claiming its advertising claims breached the federal Consumer Protection Act (CPA).

Other states are expect to file similar suits, and in the Washington filing, state officials claim that 5-Hour’s makers – Living Essentials, and major shareholder Innovation Ventures – misled consumers with their adverts under a number of heads, including claims about the brand’s functionality.

'The Attorneys General are grasping at straws!' 5-Hour Energy

5-Hour Energy hit back today in a statement sent to BeverageDaily.com: “When companies are being bullied by someone in a position of power, these companies roll over, pay the ransom, and move on. We’re not doing that. The Attorneys General are grasping at straws, and we will fight to defend ourselves against civil intimidation," a spokeswoman said.

"The suits allege that the only ingredient in 5-hour Energy that has any effect is the caffeine. If so, are the Attorneys General going to sue Starbucks for selling coffee?" she added.

However, Washington state prosecutors insist that 5-Hour derives its potency from caffeine alone, not from vitamins, enzymes, amino acids or other non-caffeine ingredients as claimed in its adverts – a point they say also completely undermines the claimed efficacy of decaffeinated 5-Hour Energy.

Founder Manoj Bhargava under fire for 2012 caffeine comments

Washington’s top state lawyers insist the brand has no “competent and reliable scientific evidence” to back claims its B-vitamin content brings energy and its amino acids focus.

Prosecutors take issue with comments from 5-Hour Energy founder, former monk and Indian entrepreneur Manoj Bhargava, who claimed in a rare April 2012 interview that the purpose of including caffeine is to help the body absorb other nutrients in the dietary supplement.

"Most of the people don't know that one of the great qualities of caffeine is it allows you to absorb nutrients and it does it quickly, and so when it does it quickly, you focus and when you focus you think you have energy," Bhargava told NDTV.com.

“In fact, the vitamins and amino acids contained in 5-Hour Energy are typically present in the normal diet of an otherwise healthy individual and amounts consumed in excess of bodily needs are typically excreted,” Ferguson and his colleagues claim.

“Describing normal metabolic functions of nutrients, then claiming that mega-doses of those nutrients provided by 5-Hour Energy will cause consumers to function at an enhanced level, is false.”

Washington claims 5-Hour misstated doctors' survey results

Washington state takes issue with other 5-Hour Energy claims, insisting that the brand’s own sponsored clinical trial shows it causes a ‘moderately severe [caffeine] crash’ for 24% of consumers.

Its lawyers insist in Washington state's filing - you can read it in full here - that a ‘no sugar crash’ tagline implies the shot won't cause a crash of any kind.

And attacking 5-Hour for its 2012 ‘Ask Your Doctor’ TV campaign, Ferguson et al. said the brand misstated the number of doctors surveyed, the results – it claimed 73% of 3,000 surveyed would recommend a ‘low-calorie energy supplement’ – and surveyed them using unsound methodologies.

State lawyers also attacked 5-Hour for sports endorsements, TV advertising slots and labeling stating that 5-Hour Energy should not be drunk by under-12s, which they said implied it was suitable for older adolescents.